1.A hard and sharp-pointed projection from a woody stem; usually, a branch so transformed; a spine.
2.(Bot.) Any shrub or small tree which bears thorns; especially, any species of the genus Crataegus, as the hawthorn, whitethorn, cockspur thorn.
3.Fig.: That which pricks or annoys as a thorn; anything troublesome; trouble; care. "There was given to me a thorn in the flesh, the messenger of Satan to buffet me." "The guilt of empire, all its thorns and cares, Be only mine."
4.The name of the Anglo-Saxon letter. It was used to represent both of the sounds of English th, as in thin, then. So called because it was the initial letter of thorn, a spine.
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